The present invention is generally related to testing and calibrating optical devices, such as those used for minimally invasive surgery. In particular, the present invention is related to methods and devices for inspecting and calibrating a stereoscopic endoscope.
Minimally invasive medical techniques are aimed at reducing the amount of extraneous tissue which is damaged during diagnostic or surgical procedures, thereby reducing patient recovery time, discomfort, and deleterious side effects. The average length of a hospital stay for a standard surgery is significantly longer than the average length for the equivalent surgery performed in a minimally invasive surgical manner. Patient recovery times, patient discomfort, surgical side effects, and time away from work are also reduced with minimally invasive surgery.
The most common form of minimally invasive surgery may be endoscopy. Probably the most common form of endoscopy is laparoscopy, which is minimally invasive inspection and surgery inside the abdominal cavity. In standard laparoscopic surgery, a patient""s abdomen is insufflated with gas, and cannula sleeves are passed through small (approximately xc2xd inch) incisions to provide entry ports for laparoscopic surgical instruments.
The laparoscopic surgical instruments generally include a laparoscope for viewing the surgical field, and working tools defining end effectors. To perform surgical procedures, the surgeon passes these working tools or instruments through cannula sleeves to a desired internal surgical site and manipulates the tools from outside the abdomen. The surgeon often monitors the procedure by means of a television monitor which displays an image of the surgical site via the laparoscopic camera. Similar endoscopic techniques are employed in, e.g., arthroscopy, retroperitoneoscopy, pelviscopy, nephroscopy, cystoscopy, cisternoscopy, sinoscopy, hysteroscopy, urethroscopy, and the like.
Minimally invasive telesurgical systems are now being developed to increase a surgeon""s dexterity, so that the surgeon performs the surgical procedures on the patient by manipulating master control devices to control the motion of servomechanically operated instruments. In such a telesurgery system, the surgeon is again provided with an image of the surgical site via an endoscope. In both telesurgical and manual endoscopic procedures, the endoscope may optionally provide the surgeon with a stereoscopic image to increase the surgeon""s ability to sense three-dimensional information regarding the tissue and procedure.
When imaging a target site with stereoscopic imaging optics, it is of particular importance to have very accurate adjustments between the stereo channels to provide accurate three dimensional information that can be matched between the two channels. If accurate matching is not accomplished, the stereo viewer will provide an inaccurate image and may cause eye strain for the user.
Consequently, it would be desirable to provide methods and devices which can inspect and calibrate a stereoscopic imaging device so as to be able to determine how well matched a first channel is compared with a second channel.
The present invention relates generally to testing and calibrating stereoscopic imaging devices, such as a stereoscopic endoscope.
In particular, the present invention provides methods and devices for inspecting an optical endoscope assembly to ensure that a first and second channel are properly focused. The methods of the present invention can be used during quality control checks after manufacturing, by end users prior to performing surgery, or by technicians that service the endoscopes to ensure the that left and right channels of the stereoscopic endoscope are properly focused.
In some embodiments, the methods and devices of the present invention can make use of a generated fringe pattern that provides information about the diopter difference between two channels of the optical endoscopes. In exemplary configurations, the fringe pattern is generated by a shear plate that reflects a light beam exiting one of the channels of the endoscope and reflects the light beam onto an imaging device. The reflected light off of a front surface and a back surface of the shear plate create a constructive and destructive interference which lead to a series of light and dark fringes or a series of straight line segments. Measurement of the angle of the straight line segments, and a comparison of the angles from a first channel and a second channel of the endoscope provides information regarding the diopter difference between the first and second channels.
Once the diopter difference is measured, the user can determine if maintenance or replacement is needed. In general, if the diopter difference between the first channel and second channel is less than approximately xc2x10.2 diopters, the endoscope will not require maintenance or replacement. It should be appreciated however, that an acceptable diopter difference between other stereoscopic imaging channels will vary depending on the type of stereoscopic imaging device, the use of the stereoscopic device, and the like.
In one aspect, the present invention provides a method of calibrating a first channel and a second channel of a stereoscopic imaging device. The method comprises comparing an angle of a straight line segment of a fringe pattern obtained from the first channel with an angle of a straight line segment of a fringe pattern obtained from the second channel to determine an angle difference between the first channel and second channel. Thereafter, the angle difference can be used to calculate a diopter difference between the first and second channel.
In exemplary configurations, the fringe pattern of the first and second channels is obtained by delivering a laser beam through the channel and reflecting the laser beam after it exits the channel off of a shear plate so as to create the fringe pattern. Thereafter, the angle of the straight line segment of the fringe pattern of the channels can be measured.
In another aspect, the present invention provides a method for calibrating a stereoscopic endoscope. The method includes a step of providing a stereoscopic endoscope comprising a first channel and a second channel. The first channel and second channel each include a first end and a second end. A laser beam is delivered into the first ends of the of the first and/or second channel so as to emit light through at least one of the second ends of the first channel and second channel. The light that exits the second end of the first channel and the second channel can be reflected off of a fringe pattern device, (e.g., a shear plate). The fringe pattern device can create two beams of light that create a fringe pattern comprising straight line segments. An angle of the straight line segments for the first channel and second channel can be measured and the measured angle of the First channel and the second channel is calculated to determine a diopter difference between the first channel and the second channel.
In a further aspect, the present invention provides a method of calibrating a stereoscopic imaging device. The method includes a step of obtaining a fringe pattern for the first imaging channel. An angle of a straight line segment of the fringe pattern for the first imaging channel is calculated. A fringe pattern for the second imaging channel is obtained and an angle for a straight line segment of the fringe pattern for the second imaging channel is calculated. The angles of the first imaging channel and second imaging channel are compared and a diopter difference between the first imaging channel and the second imaging channel from the comparison of the angles is calculated.
In yet another aspect, the present invention provides a system for calibrating a stereoscopic imaging device. The system comprises a stereoscopic imaging device having a first channel that has a first end, a second end, and an optical assembly between the first end and the second end. The stereoscopic imaging device also includes a second channel comprising a first end, a second end, and an optical assembly between the first end and the second end. A laser that generates a laser beam along an optical axis is positioned so that the laser beam enters at least one of the first ends of the first channel and second channel and is emitted through the optical assemblies. At least one compensator lens is positioned adjacent the second end of the first channel and right channel such that the compensator lens collimates diverging light that exits the second ends of the channels. At least one shear plate is positioned to receive the collimated light after it exits the compensator lens. The shear plate creates for the first channel and second channel an interference fringe pattern having straight line segments that define an angle that varies with a diopter of the optical assemblies of the first channel and second channel. A difference in the angles of the straight line segments of the first channel and second channel is used to calculate a diopter mismatch between the first channel and second channel.
In another aspect, the present invention provides a device for calibrating a stereoscopic endoscope. The device includes a stereoscopic endoscope having a first channel and a second channel. A laser source is positioned to deliver a laser beam along an optical axis and into at least one of the first channel and second channel. A fringe pattern device that can generate a fringe pattern from light that exits the first channel and second channel. An image device captures at least one image of the fringe patterns. A controller assembly is in communication with the image device and is configured to calculate an angle of the fringe pattern, determine an angle difference of the fringe patterns, and determine a diopter difference between the first channel and second channel using the angle difference.
In yet another aspect, the present invention provides a kit for focus matching a first channel and a second channel of a stereoscopic imaging device. The kit comprises a laser source that generates a laser beam and a shear plate that reflects light exiting at least one of the first channel and second channel and creates a fringe pattern from the reflected light from the first channel and second channel. The kit further includes a camera that can obtain an image of the fringe patterns for the first channel and second channel and a computer system that compares the angles of the fringe patterns of the first channel and second channel and calculates a diopter difference between the first channel and the second channel.
For a further understanding of the nature and advantages of the invention, reference should be made to the following description taken in conjunction with the accompanying drawings.